OPTIMIZING MANAGEMENT PRACTICES TO MEET LOADING TARGETS FOR THE LONG ISLAND SOUND BASIN UNDER VARIABLE CLIMATE

US EPA has previously published a decision support tool (River Basin Export Reduction Optimization Support Tool, RBEROST) populated with data for the Upper Connecticut River Basin to allow stakeholders to determine the least-cost management strategies to meet nitrogen and phosphorus loading targets both within the basin and at the basin outlet (Chamberlin et al. 2021 and https://github.com/USEPA/RBEROST). Previous work was informed by annual source loadings and attenuation factors from the US Geological Survey associated with the Northeast US Spatially Referenced Regressions on Watersheds (SPARROW) model. In collaboration with the USGS, EPA is now updating RBEROST to encompass the full Long Island Sound Basin and to incorporate N and P source loads from a dynamic SPARROW model under development by USGS. The latter will estimate seasonal loads at the NHDPlus catchment scale over a 20-year period. Incorporation of seasonal and interannual variability into RBEROST will allow users to examine how optimal management practices can vary with changing climate and will also allow evaluation of lag effects associated with changing loads and practices. The updated version of RBEROST will include information on implementation costs and nutrient reduction efficiencies for agricultural conservation practices, riparian zone restoration, stormwater best management practices, wastewater treatment plant upgrades, septic system upgrades, and septic to sewer conversions. Efforts have been initiated to implement similar tools for the Puget Sound Basin and the Upper Illinois River Basin.